Effective leveraging of solid state disk drives as a data cache is dependent on accurate detection and retention of frequently accessed data. A challenging aspect is to find the frequently accessed data by observing only a stream of host commands coming from an operating system to a controller of a redundant array of independent disks. Once detected, the data is loaded into the cache for higher performance on subsequent requests. However, if the data is infrequently accessed, cache space is wasted and performance negatively impacted because loading the infrequently access data into the cache represents additional operations.
It would be desirable to implement virtual cache window headers for long term access history.